Reduce Slowdowns and Fulfill Your Production GoalsAir Cooled Heat Exchanger Health Monitoring

With hundreds of fans, need to know where to focus?Overhead air cooled heat exchanger failure puts plant operators face to face with an industry-wide enemy: unscheduled slowdowns and process disruption. An exchanger problem can cause lost production, reduced margins, overextended maintenance budgets, and recordable incidents—including the possibility of a government audit.

In a cooling-limited operation, losing one fan can lead to a recordable incident if the fan affects a distillation column’s overhead receiver and causes the relief valve to lift. Should the relief valve fail to reseat, then not only will this constitute another recordable incident, but a shutdown will also be required to fix the unseated valve.

Other factors such as freezing temperatures, dust or oil fouling the heat transfer areas, and an inability to cool hot chemicals can cause maintenance woes and environmental incidents. These common issues can increase costs and make it difficult to meet production goals, particularly if a repair requires overtime pay and expedited parts. The situation only becomes worse if root causes are undetected and repeat failures occur.

Anatomy of an Overhead Air Cooled Exchanger Failure

Root Cause EquipmentImpact

ProcessImpact

EnvironmentalImpact

Business Impact

UndetectedConditions

AvoidableConsequences

AbnormalSituations

Belt/couplingfailure

Faulty louverposition

Freezing withinfinned tubes

Replacement ofruptured/leaking

finned tubes

Vapor release

Process leak

Flare

Products tostorage tankstoo hot-tank

over-pressure

Unit shutdown Increasingmaintenance

costs

Distillationcolumn

over-pressurerelief valve lift

Belt/couplingnormal wear

and tear

Ambient conditions(freezing

temperatures)

Increasedvibration

and bearingtemperature

Reportablefines

Evening newsRebuild costs

Human impact

Reduced unitthroughput

Fan blades stop

Exchangerfouling

Resonancefrequency

Dust buildup ontubes or corrosion

Bent louver arm

b d

Stuck louverSt k l

Misaligned louverpositioner

R

Bearing normalwear and tear

Cooling reduced

Common Threats to Air Cooled Heat Exchanger Health

BAD INSTALLATIONImproper installation can lead to shaft misalignment and excessive vibration, resulting in fan damage and possible failure.

LOUVER/PITCH ACTUATOR MECHANICAL DEFECTSFaulty louver or pitch actuator position can restrict airflow and reduce cooling capacity, leading to diminished unit throughput. Root causes can include broken or bent louver arms, a misaligned louver positioner, and stuck louvers.

HIGH VIBRATION AND BEARING TEMPERATUREIncreasing motor or fan vibration and bearing temperature can result in belt and coupling failure or can cause fan blades to stop. Root causes can include bearing normal wear and tear, operation at resonance frequency, and mechanical support failures.

EXCHANGER FOULINGLimited cooling is an indication of exchanger fouling. This can reduce the cooling capacity of the exchanger, leading to diminished unit throughput. In addition to other process impacts, fouling can cause products heading to storage tanks to become too hot, resulting in possible environ-mental or health and safety issues. Root causes can include dust buildup on tubes or corrosion.

With hundreds of fans, need to know where to focus?What if you could...Reduce Unplanned ShutdownsKeep a closer eye on fan vibration, bearing temperature and overall asset health without having to increase manual maintenance checks. Discover abnormal situations or subtle variations such as temperature changes before they cause problems, slowdowns, or shutdowns.

Increase Asset ReliabilityUncover the root causes behind “bad actor” equipment. Perform maintenance on your exchangers only when required and in time to prevent failure. Reduce the costs incurred by repeat failures and unnecessary preventive maintenance.

Mitigate Safety and Environmental RisksReceive early warning of potential fan failures and resulting safety hazards before they become plant-wide problems. Reduce reportable incidents through early detection. Limit the number of trips into potentially hazardous plant areas for maintenance or data collection related to fan vibration and bearing temperature.

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Chemical

Air CooledHeat Exchanger Solution

Emerson’s overhead air cooled heat exchanger health monitoring solution gives operators greater confidence and control over asset planning by replacing manual, periodic reading with automated monitoring that indicates abnormal operation and allows for alarm, analysis, trending, and historization. Automated monitoring will allow you to know about and respond to real-time condition changes such as fluctuations in vibration and bearing temperature, which can cause exchanger failure, fouling, and damage. Wireless installation and monitoring reduces your installation-related costs and frees personnel from manual trips to hazardous plant areas, allowing them to focus their energies on other vital areas.

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Increasing your profitUnscheduled shutdowns and slowdowns are a leading cause of lost profit opportunities. What assets are contributing to this number at your plant?

INPUTa. Plant capacity in tons per day 1,700b. Plant net margin per ton $200c. Operating time in days per year 365d. Capacity utilization 0.93e. Plant total annual maintenance spend, excluding turnarounds $40,000,000f. % of production capacity lost due to ACHE failure 0.70%g. % of plant total annual maintenance attributable to ACHE 0.90%h. Process ACHE not currently monitored 30

OPERATIONAL BENEFITSi. % reduction in lost production with ACHE monitoring 30%Annual Net Profit Improvement (=a x b x c x d x f x i) $242,367

MAINTENANCE BENEFITSj. % anticipated reduction in ACHE maintenance cost with diagnostics 30%k. Annual maintenance budget per ACHE (= e x g/h) $12,000Annual Maintenance Savings (= h x j x k) $108,000

TOTAL ANNUAL IMPROVEMENT $350,367

NotesThis is an example of an olefin plant.

Emerson Overhead Air Cooled Heat Exchanger Monitoring Products

Emerson Process Management1100 W. Louis Henna Blvd.Building OneRound Rock, Texas 78681-7430www.EmersonProcess.com/Chemical

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SOFTWARE INTERFACE

ADDITIONAL OPTIONS

NETWORK INTERFACE DEVICES

AMS SUITE: ASSET GRAPHICS FOR OPERATIONSProvides real-time graphical displays that indicate abnormal operation, including resonance frequency detection, louver defects, exchanger fouling detection, and overall exchanger health. A pre-engineered algorithm delivers diagnostic information for alarms, process analysis, trending, historization, and key performance indicators.

AMS SUITE FOR MAINTENANCEAids early identification of asset problems using predictive diagnostics, allowing maintenance to schedule repairs while reducing cost and downtime.

FISHER WIRELESS POSITION MONITORIndicates equipment position with a percent of span plus on/off indication. Monitors louver position for mechanical defect detection.

CSI WIRELESSVIBRATION TRANSMITTERProvides early warning of excessive vibration in heat exchangers. Helps determine root cause and guides corrective action. Optional functionality can identify premature bearing wear and predict failure.

ROSEMOUNT WIRELESSTEMPERATURE TRANSMITTEREnables temperature measurements to determine heat transfer efficiency on exchangers. Ideal for this high performance application to enable optimization of exchangers at a low cost.

ROSEMOUNT WIRELESSTEMPERATURE TRANSMITTEREnables (high density) temperature measurements to determine heat transfer efficiency on exchangers. Ideal for this high performance application to enable optimization of exchangers at a low cost.

SMART WIRELESS GATEWAYConnects IEC 62591 (WirelessHART®) self-organizing networks with any host system.